[Richard]

Yes, to the wet tank

There should be a check valve very close to the exit of the 110V compressor. As should there be some sort of mechanism to relieve the pressure on the compressor so it doesn't have to start against a high pressure.

Air leaks are so much harder to diagnose than electrical problems. If you suspect air is leaking out the 110V compressor. Disconnect the air line at the compressor and dead head it. Crank the engine and build air pressure. Compare the leak rates with and without the compressor connected. That will answer your question.